Leadoff is a popular residual option in an early burndown program. Leadoff is a premix of the SU herbicides rimsulfuron and thifensulfuron. It will provide several weeks of residual control of winter annual weeds and will help curtail regrowth of horseweed that has been injured by dicamba that otherwise might re-grow.  It also will aid in control of ryegrass and poa over glyphosate alone.

On the management side, do not expect Leadoff to control existing horseweed as it will need to be mixed with dicamba and glyphosate to do a thorough burndown of horseweed. Please note there is a 30 day plant back to cotton and soybean after a Leadoff application.  Under cool, wet and higher pH soils, some non-STS soybeans can have their early growth checked up some where Leadoff has been used. In corn it can be applied clear up to planting.

Valor, Sharpen and Verdict are the other popular residual herbicides typically used in an early burndown. Of course, Sharpen and Verdict will also do a good job on controlling existing horseweed. The main reason to utilize any residual herbicide in early March is for residual winter annual control.  Leadoff, Valor, Sharpen and Verdict will all provide about the same amount of residual control for winter annuals.  Please do not expect residual Palmer control from these applications.

There is no residual herbicide that will typically provide any measurable Palmer amaranth control in soybeans or cotton when applied during most of the month of March.  Also we need to be more wary of Italian ryegrass this spring, which I will touch on in another blog.